Rotary debarker having pivotal barkremoving tools biased by elastic rubber



March 26, 1957 p. G. BRUNDELL ETAL 2,786,499

ROTARY DEBARKER HAVING PIVOTAL BARK-REMOVING TOOLS BIASED BY ELASTICRUBBER Filed March 22, 1954 4 Sheets-Sheet 1 IN VEN TORJ f. 6 .firzuuieLL KIELdL/OIZGJ 017 WWW March 1957 P. G. BRUNDELL ET AL 2,786,499

ROTARY DEBARKER HAVING PIVOTAL- BARK-REMOVING TOOLS BIASEID BY ELASTICRUBBER Filed March 22, 1954 4 Sheets$heet 2 I N VEN TORS f? 6. ERUNDE LLK-E. A. JONSSON ATTORNEYS March 1957 P. G. BRUNDELL ET AL 2,786,499

ROTARY DEBARKER HAVING PIVOTAL BARK-REMOVING TOOLS BIASED BY ELASTICRUBBER Filed March 22, 1954 4 She'ets-Sheet 3 INVENTQgiL BYJYEA .J01265010 BRUNDELL EIAL ROTARY DEBARKER HAVING PIVOTAL. BARK-REMOVINGMarch 26, 1957 TOOLS BIASEZD BY ELASTIC RUBBER 4 Sheets-Sheet 4 FiledMarch 22, 1954 INVENT-ORS .P. GDrwndeZL BYlEETfl.Jozzaoaz2/ UnitedStates PatentO ROTARY DEBARKER HAVING PIVOTAL BARK- REMOVING TOOLSEIASED BY ELASTIC RUB- BER Per Gunnar Brundell, Gayle, and Karl-Erik'Arnold .lonsson, Borlange, Sweden, assignors to Soderhamns VerlrstadersAktiebolag, Soderhamn, Sweden Application March 22, 1954, Serial No.417,814

Claims priority, application Sweden March 30, 1953 14 Claims. (Cl.144-208) During recent years a number of debarking machines of thehollow-head type have been constructed for debarking pulpwood andtimber. These mchines are such that successive logs are fed through thehollow-head of the machine along a straight path and without rotation,while a plurality of tools, mounted in a frame or rotor which rotatesaround the path of travel of the logs, are resiliently pressed against alog with such force that the bark is removed along helical paths by africtional or shearing action. The resilient force pressing the toolsagainst the logs has hitherto been generated by means of compressed air,balance weights or steel springs.

The present invention is principally characterized by the use of solidelastic materials for the actuation of each tool, carried by a swingablearm, so that, if straight lines are drawn from the point or points ofattachment of this material to the rotary frame to its point or pointsof attachment to the tool arm or to levers connected to pivot shafts ofthe tool arms, such straight lines will always lie within the elasticmaterial. The actuating force thus is effected directly and without anyspecial means such as spiral winding and the like, since either thestretching of elongate elastic material will produce tensile stress orthe application of torque to a bushing of elastic material will produceshearing stress.

The resilient elastic force is generated by means of shearing or tensionin a suitable elastomer. preferably natural rubber compounded withcarbon black. The use of such material gives results comparable to theuse of either steel springs or compressed air, but avoids the' problemsof leakage thatalways accompanies the use of compressed air. Incomparison with steel springs the rubber provides a damping efiect whichprevents troublesome vibrations, whereas steel springs tend to oscillatelongitudinally and also transversely when the tools'ride over anirregular log surface. The actuation of the tool by rubber means isextraordinarily smooth which is particularly apparent in comparison withmachines using balance weights for the actuation of the tools. Thestructure of the machine can be'made much lighter due to the fact thatit is not necessary to pay the same attention to fatiguing shockstresses as by machines using another form of actuation of the tools.Due to the light weight of the rubber member itself in relation to thedesired actuating force, its small demand of space and the indirectdecrease of weight due to the fact that the construction further can bemade lighter it has become possible to produce a lightweight machine.ferent embodiments of the invention are shown as examples in connectionwith the following figures.

Figure l is a fragmentary view of a debarking machine with parts brokenaway for clarity as viewed from the direction of log feed andillustrating one form of the invention as regards means for applying thedebarking tools to the logs, p I

Figure la is a fragmentary view diagrammatically illus- Some diftratingcertain angular relationships of the parts shown in Figure 1,

Figure 2 is a fragmentary side view partly in elevation.

and partly in section with the section being taken on lines 2--2 ofFigure 1,

Figure 2a is a fragmentary sectional view taken along lines Za-Za ofFigure 1,

Figure 3 is a view similar to Figure 1 but illustrating a modifiedarrangement of debarking tools and the means for applying force thereto,

Figures 4 and 4a are fragmentary views partly in elevation and partly insection of the upper part of Figure 3, as taken along lines 4-4 and4a--4a, respectively, but omitting the stationary frame,

Figure 5 is a fragmentary view illustrating a modified form of mountingand force-applying means for the tools,

Figure 6 is a cross-sectional view taken along lines 6-6 of Figure 5,and

Figure 7 is a cross-sectional view taken along lines.

7-7 of Figure 5.

In Figures 1 and 2, It) designates an annular rotor rotatably journalledin a stationary frame 12 by means of a bearing 14. The rotationalmovement of the rotor 10 is effected by means of V belts 16. Logs 18 arefed seriatim through the center of the rotor in a straight path by anyknown feeding means. in the rotor are mounted three barking toolscarried by swingable arms 13, the toolcarrying ends of the arms 13 beingcontinuously biased toward an axis of rotation 34 of the rotor 10. Thesetools may be of arbitrary type but preferably are made in such a mannerthat they remove the bark by means of shearing, the swingable arms beingof such a shape that when they are contacted by an oncoming log, theyare automatically swung outward as they ride over the butt end of thelog, the tools thus being moved onto the peripheral surface of a logwithout making any change in the force that initially biases the armstoward the rotor axis. Shafts 20 of these arms are journaled in bearings22 in the rotor 10. The shafts 20 are connected with levers 24 havingoutwardly extending arms 26, in each of which arms is a hold or pin 27for one or several ring-shaped rubber members 28. This hold ispreferably journaled on a needle hearing in order that the rubber willnot become worn by sliding when the swingable arm and thereby also thehold or pin pivots. The pivoting angle of the arm generally amounts toabout 30 to 40 degrees. it is preferable to arrange the arm 26 of thelever 24, when the tool is in its inner position, so that an interiorangle between a plane containing the axis of the shaft 20 and the holdor pin 27 and the acting line of the tensive force of the rubber willfall within a range of about 70 to degrees, Figure 1b. When the toolmoves from the minimum to the maximum diameter of the log the increaseof the tensive force of the rubber is compensated by a correspondingdecrease of the effective lever, i. e. the perpendicular distancebetween the acting line of the tensive force and the axis of the shaftof the swingable arm. In this manner a much smaller rubber length isrequired for keeping the actuating force within permissible limits atthe outer and inner position of the tool than if the lever is arrangedso that said perpendicular distance remains constant. is disposed in itsoutermost position, the best relation is obtained when the planecontaining the axis of shaft 21 and of hold or pin 27 forms an interiorangle of about 40 to 50 degrees with the line of action of the tensiveforce, see Figure la. The rubber band 28 is at its outer end connectedwith a holder 30, which by means of a screw 32 can be displaced inrelation to the rotor 10 so Patented Mar. 26, 1957 When the tool thatthe initial force that biases the barking tool can be varied fordifferent barking conditions. Other ways to vary the initial biasingforce,.which can be combi ed with the displaceablc holder 39 comprisesremoving or adding rubber bands 28, and selecting rubber bands having adifferent modulus of lasti ity. The movement of the swingable arm 13towards the rotation axis 34 of the rotor is limited by contact betweenstops 36, mounted on the rotor 19 and preferably provided with rubbercushions, and two arms 38 of the lever 24. The change in the tensivcforce of the rubber member 28 is initially cted when the screw 32 isdisplaced by rotation of a worm gear 40 mounted in suitable bearing andsecured to the rotor, through the threaded center of which gear thescrew passes. The worm gear til} is in its turn rotated by a worm screw42 which is also mounted on the rotor and which can be turned by asuitable key in the keyholc 44. As an example it may be mentioned thatin a barking machines intended for logs having a diameter of 2" to 16",each tool required three rubber rings each having a square section of 2crnfi. The eifective length of the rubber in unstretched condition was80 mm. The weight of all rubber members for the setting amounted toabout 0.35 kg. The modulus of elasticity of the rubber was 1.6 kg./cm.As a comparison it may be mentioned that the weight for correspondingsteel springs amounts to about kg. The arrangement with balance weightsand air-pressure cylinders respectively will be still heavier. Becauseof the small weight of the rubber used in the arrangement described, theinfluence of centrifugal force will be small in comparison with thatobtained when using a steel spring.

Figure 11) illustrates a modified arrangement for regulating the tensionof the rubber bands. In this figure an endless rubber band 148 has oneend secured to the pivot or pin 27 while its other end is connected to astud means 14-6 that is carried by the end of a piston rod 144 securedto a piston 1 .2 displaceable in a cylinder 14%). The cylinder isconnected at one end to a pin 1.52 that is mounted in bearings orholding means 155? secured to the rotor whereby the cylinder 140 canrock about an axis parallel to the axis of the rotor. A stuffing box 154closes the opposite end of cylinder Md and the piston rod passestherethrough. In order to introduce fluid into the cylinder 140 in frontof piston 142 a flexible conduit 158 communicates with an inlet 156 inthe cylinder. The flexible conduit in turn is connected to a circularconduit 166 carried by the rotor and in turn in fluid communication withother cylinders like 1 51) that are associated with the other tool arms,not shown. A pressure gauge 166 is in communication with the circularconduit 169 and to introduce fluid into the circuit a conduit 164communicates with the circular conduit 16%. A control valve 152 ismounted in the conduit 164. It is believed clear that liquid can beforced into the hydraulic system by hand pump, not shown, adapted forcoupling with the conduit E64. inasmuch as the liquid circuit is incommunication with all of the piston cylinders, introducing the liquidunder pressure at one point will place the same pressure in eachcylinder so that the tension of the rubber bands 148 will be equal foreach tool. Any difierences between the rubber bands as occasioned bydifferent settings will automatically be compensated for. The pressuregauge 166 will furnish a reading that is proportional to the actuatingforce or" a tool against a log.

it is clear therefore that both in Figures 1 and lb the endless rubberband constitutes anelastically deformable means for applying force tothe tools during debarking and that by means of axial movement of thescrew 32 or the piston 142 the amount of tension in the bands and thusthe force applied to the tools can be adjusted to suit differentdebarking conditions.

Figures 3 and 4 illustrate a further mo ifica i n in which anelastically deformablemeansis utilized. in this arr ngem n here is showna further concept in the use of rubber in the construction of thebarking machine as not only the biasing force but also the journaling ofthe swingable arms is effected by means of rubber. The barking machineaccording to Figure 3 is provided with five barkremoving tools and has arotor 45, a stationary frame 46, a rotor bearing 48 and a driving device5b in the same manner as described in connection with Figure l. Shafts54 of the swingable'arms 52 are fixed by means of vulcanization inpreferably cylindrical rubber sleeves 55 attached to the rotor 45 bymeans of tubular metal jackets The shaft 54 of the swingable arm isprovided at its front end with an enlarged end portion against which theswingable arm 52 is fastened by a flat head screw 60. A small lever 6%is mounted at its midportion on an Opposite end of the. shaft and eitherengage a pair of stops 56 to limit the turning movement of the swingablearm towards the center, or engages a single stop 66 to limit outwardswinging movement of the arm. The lever 64 can be fixed in differentpositions in relation to the shaft by means of a screw in order toobtain the desired initial biasing force of the barking tool. This iseffected by turning the shaft by any suitable device, through such anangle that a torque proportionalto the desired initial biasing force isobtained from shearing stresses set up in the rubber. The swingable armof the tool and the stop levers are thereafter screwed tight in relationto the shaft. The machine is now to be used for its purpose. Thisembodiment of the in vention is characterized by an utmost'soft runningas the barking tools are not in metallic connection with the rotor.Another reason for the smooth running is that the rubber bushing permitsa comparatively great fi371Dlllty in all directions for the swingablearms so that the tools can adapt themselves along the log surface. Theflexibility of the bushing in the longitudinal direction of the log isdesirabl when using swingable arms formed for auto matic opening uponcontact with the butt end of an oncoming log. Some further advantagesinclude an extreme simplicity in construction by requiring a smallnumber of parts, an insensibility to the climate, and operabilityunderrough conditions in the forest. Furthermore ordinary bearing friction isavoided as well as lubrication, and'in addition the rubber bushing doesnot require maintenance. Due to the small external diameter of therubber bushing the dimensions of the rotor can be decreased to aminimum.

In Figure 5 a shaft 92 to which a barking tool arm 94 is attached bymeans of a flange 96 and bolts 98 is surrounded by a sleeve 104 attachedto a hollow head 1% by means of a clamping ring 102. On the inner sideof this sleeve there are three longitudinally arranged ridges 106,Figure 7. To the shaft 92 there are attached by vulcanization two rubberbushings 108 of the same size, and each having concave end walls whichprogressively decrease in-diameter as they curve away from one anotherand towardthe shaft 92. Preferably the lengths of any two lines whichlie parallel to an axis 110 of the shaft 92 and which extend betweensaid concave end walls and. within said bushings, is made inverselyproportional to their distances from said axis 110 of the shaft 92. Bydoing this the permissible turning angle for the barking tool inrelation to the hollow head will be the greatest possible withoutcausing any cylindrical section of the rubber to have less resistance toaxial stresses along the axi 110 than the section closest to the shaft9.2. The provision of two bushings coupled in parallel will result in anincreased resistance against forces which tend to rock the shaft 92 outof its concentric relation with sl eve 194. To the outside of each ofthe bushings 108, are vulcanized three peripherally spaced section 112of a sleeve member. During manufacture the diameter of the bushings aresuch that they have to be pressed into the sleeve 104. By doing thistherubber can be given desired compression resulting in a betterdurability. The sleeve sections 112 fit between the ridges 106 and preofa clamping device 120 this sleeve is attached to a collar,

122 on the hollow head. The movement of the barking tool towards theaxis 34 of the hollow head is braked by rubber members 126 providedbetween the ridges 116' and the wings 114. The end point of the movementof the debarking tool can be determined as desired by loosening theclamping device 120 and then turning the sleeve 118 until the desiredposition of the tool is reached. The desired initial actuating force onthe tool is brought about by loosening the clamping ring 102 after whichthe sleeve 104 is turned by aid of a key that fits a key hole 124 untilthe desired actuating force is attained, after which the clamping ringis tightened. The above described construction is simple and easy tomanufacture and very robust. The initial actuating force of the tool caneasily be regulated within desired limits. The device is very compactespecially in its radial dimensions. For example, a debarking machinefor a smallest log dimension of 1" and a largest dimension of 11", thediameter of theshaft 92 was 1 and the inner diameter of the sleeve 1042%". The total greatest length of the rubber bushings 108 along theshaft 92 was 7'. The torsion modulus of the clastomer used is preferablybetween 3.5 and 8 kg./ cm. "(5 v to 115 p. s. i.) and is preferablychosen to; be between and 6 kg./cm. (70 to 85 p. -s. i.). Turninganglesfrom inner 9 to outer position of the debarking tool can amount up to 45without the resulting difference in actuating force exceedingpermissible limits of variation.

It is therefore clear that the present invention provides a debarkingmachine of the type in which successive logs are fed end to end througha rotary annular frame while the logs are restrained against rotation. Aplurality of arms are mounted on the frame for movement toward and awayfrom the axis thereof and elastically deformable means are carried bythe frame and operably coupled to the arms for exerting a resilientforce thereon to apply debarking tools or bark removing portions of thearms against a log with sufficient intensity regardless ofirregularities in log contour or bark to remove the bark from the logsas the frame rotates thereabout. The elastically deformable means ishoused within the rotary frame in one form and constitutes at least one.endless rubber band for each arm operable by tension. 'Me ans areprovided for adjusting the tension exerted by the bands to suit dif-'ferent debarking conditions.

In another form of the invention the elastically deformable meansconstitute rubber bushings simultaneously supporting a shaft carryingeach arm and placed under shear stress so as to apply force to the arm.In other words, the rubber bushings are vulcanized internally to a pinor pivot operably connected with the arms and externally either directlyor indirectly to a portion of the rotary frame. In these forms, meansare provided for adjusting the shear stress to thereby adjust the forceapplied to the arms.

What we claim is: I I

1. In a debarking machine, a rotatably mounted annular frame throughwhich logs to be debarked are fed in end-to-end relation and whilerestrained against rotation, a plurality of debarking tools carried bythe frame, turnable shaft means carried by the frame, extending parallelto the axis of rotation of the frame and mounting the tools for movementtoward and away from the axis of the frame in paths containing a planetransverse to said axis, solid-elastic-rubber-material means adjustablyconnected between each shaft and the frame for applying a resilientturning and actuating force to each of the shafts to move the respectivetool in the direction toward the axis of the frame with a forcesuflicient to remove bark equally spaced around the frame, each of saidarms having substantial length, the solid-elastic-rubber-material' fromlogs,- and co -operable stop means respectively carried by the frame andshafts to limit the movement of said shafts and thus of said toolstoward the axis of the frame.

2. In a debarking machine as claimed in claim 1, in which thesolid-elastic-rubber-material means constitutes rubber strip meansadjustably connected in tension between the frame and each shaft. 1

3. In a debarking machine as claimed in claim 1, in

which the solid-elastic-rubber-material means constitutes at least onerubber bushing connected in shear between the frame and each tool.

4. In a debarking machine as claimed in claim 1, and

the means mounting each tool including an arm, each arm having an outerend, a pin secured to the outer end and extending parallel to the axisof the frame and the solid-elastic-rubber-material means constituting,for each arm at least one rubber bushing having its inner surfacevulcanized to the pin and means including vulcanization .fixing theouter surface of the bushing to the frame, and

means for adjustably imparting shear stress to each bushing in order toinitially adjust said turning and actuating force.

5. In a debarking machine as claimed in claim 4, in

-which each rubber bushing is of varying cross section with the widthdecreasing from the central portion thereof toward the opposite ends. 6.In adebarking machine of the type in 'which a suc cession of logs to hedebarked are fed forwards in end to-end relation while restrainedagainst rotation-through a rotary annular frame, the improvementscomprising, a plurality of debarking tools carried by the frame, pivot.means mounting the tools for movement toward andaway from the axis ofrotation of the frame, andsolide elastic-rubber-material strip meansadjustably' connected in tension between the frame and each of the toolsfor applying force thereto in a direction extending toward the axis ofthe frame so as to apply the tools to a log 'with sufficient intensityregardless of irregularities in log contour or bark to remove such bark.

7. In a debarking machine as claimed in claim 6, in

which swingable arms carry the tools, the pivot means mounting the toolsincluding shafts journalled on the frame and extending parallel to theaxis thereof, said arms being mounted on said shafts, said shafts beingstrip means normally biasing the arms inwards in the direction towardthe axis of the frame and stop means carried respectively by said shaftsand said frame to limit the inward movement of the arms under the forcegenerated by said strip means so that the tools carried by therespective arms are maintained out of contact with one another.

8. In a debarking machine of the type having a rotary annular framethrough which a succession of logs to be debarked are fed forwards inend-to-end relation while restrained against rotation, the improvementscomprising, a plurality of debarking tools, shafts journalled on theframe, said shafts extending parallel to the axis of rotation of theframe and corresponding in number to the number of tools, an arm mountedon each shaft so as to turn therewith, said arms carrying the tools,solidelastic-rubber-material means operably connected with each of thearms for applying turning force thereto in a direction to move the toolcarried thereby toward the axis of the frame and to apply the tool to alog with sufiicient intensity regardless of irregularities in logcontour or bark to remove such bark, lever means connected to eachshaft, said solid-elastic-rubber-material means comprising at least oneendless rubber band for each arm, means coupling one end of each band toeach lever means in a manner to apply said turning force thereto andmeans mounting the other end of each band for movement toward and awayfrom the associated lever means so as to permit adjustment of thetension exerted by the bands on the. levers and thus on the arms tothereby adjust the force applied to the tools to different barkingconditions.

9. In a debarking machine of the type having a rotary annular framethrough which a succession of logs to'be debarked are fed forwards inend-to-end relation while restrained against rotation, the improvementscomprising, a plurality of debarking tools carried by the frame, pivotmeans mounting the tools for movement toward and away from the axis ofrotation of the frame, solid-elastic-rubher-material means connectedbetween the frame and the tools to apply force to each of the latter ina direction extending toward the axis of the frame and to apply each ofthe tools to a log with sufficient intensity regardless ofirregularities in log contour or bark to remove such bark, saidsolid-elastic-rubber-material means comprising at least one endlessrubber band operably connected under-tension to each tool at one end andmeans adjustahly connecting an opposite end of each band to the framefor adjusting the tension of the band.

10. In a debarking machine as claimed in claim 9, in which thelast-mentioned means includes a screw extending in line with an initialline of force applied by each band when the tools are disposed in theirinnermost or inoperative position, and means for axially displacing thescrew to adjust the tension acting along the initial line of force.

11. In a debarking machine as claimed in claim 10, in

which the last-mentioned means comprises for each band a piston, acylinder for each piston, means mounting the cylinders on the rotor, andmeans for introducing fluid into each cylinder behind the piston thereinin order to alter the position of the pistons and thus vary the tensionof the bands.

12. In a debarking machine of the type having a rotary annular framethrough which a succession of logs to be debarked are fed forwards inend-toend relation while restrained against rotation, the improvementscomprising, a plurality of debarking tools, pivot means mounting thetools for movement toward and away from the axis of rotation of theframe, elastically deformable means supported by the frame and operablyconnected with the tools for applying force to each of the latter in adirection extending toward the axis of the frame so as to apply each ofthe tools to a log with sufiicient intensity regard less ofirregularities in log contour or bark to remove such bark, eachdebarking tool comprising a swingable arm, saidpivot means including ashaft for each arm journalled' in the rotary frame and extendingparallel to the axis thereof, said shaft being connected to one end ofthe arm, the opposite end of the arm constituting a log-contactingportion of the tool, lever means connected to each shaft and including afirst lever arm extending in a direction radially outward from ajournallingxis of the shaft and a pair of lever arms extending fromopposite sides of a plane containing the axis of the shaft and saidradially outward direction, the elastically deformable means comprisingat least one endless rubber band, means connecting one end thereof tothe first lever arm, means connecting the other end to the rotary frameso that an initial line of force of the rubber band makes an interiorangle of'bet'ween'70 and 90 with an initial radially outward directionof said first lever arm, when the swingablc arm isin its'innermostposition; stop means cooperating with the saidpair of lever arms tolimit the inward movement of the swingable arm to said innermostposition and said first lever arm having a length such that when theswingable arm is in its outermost position an interior angle formedbetween a terminal line of force of the rubher band and a terminalradially outward direction of said first lever arm, is between 40 and13. A debarking machine comprising a rotary annular frame through whichsuccessive logs to be debarked are adapted to be fed in end-to-endrelation while restrained against rotation, a plurality of tool-carryingarms dis-- posed for swinging movement in paths containing a planetransverse to the axis of rotation of the frame, a shaft for each arm,said shafts extending parallel to the axis of the frame and beingdistributed around and journalled in the frame, means connecting one endof each arm to its shaft, a tool at the other end of each arm, andsolidrubber biasing means adjustably connected between the a frame andeach arm and constructed and arranged to apply turningforce to the shaftto urge the arm inwardly so as to urge the tool toward the axis of theframe and to apply the tool to a log being fed with sufficient intensityregardless of irregularities in log contour and bark to remove suchbark.

14. A debarking machine as claimed in claim 13 and a lever meansconnected to each shaft, each said solidrubber biasing means comprisingan elongate rubber body, means connecting one end of each body to one ofsaid lever means, means carried by the frame and mounting the other endof each body for movement toward and'away from the associated levermeans so as to adjustably tension each body, and stop means carried bythe frame for limiting the movement of the lever means and thus of thetools toward the axis of the frame.

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